Capsule endoscopy is a new method for diagnosing diseases of the gastrointestinal tract, in particular in the upper sections of the small intestine (jejunum). This permits a patient-friendly, painless investigation of the entire region of the small intestine without physical exposure to radiation. This method of investigation has the advantage that it is possible to inspect areas in which conventional radiological and endoscope methods achieve only inadequate diagnostic results.
In this case, the patient swallows a capsule that is equipped with a miniature color video camera, supplies endoscopic images from the small intestine, and permits painless non-invasive diagnostics. It is also possible to conceive inserting the capsule in the rectum if the aim is solely to carry out a coloscopic examination of the large intestine including the terminal ileum.
The examination begins in this case after fasting and can be carried out on an outpatient basis. After activation and ingestion of the video capsule, the patient can carry on with his customary daily activities without a problem and without noticing the approximately eight-hour passage of the capsule through the gastrointestinal tract. After the capsule has spent on average approximately 80 minutes in the stomach, it requires approximately 90 minutes on average to pass through the small intestine.
Such a capsule endoscope and a diagnostic system for visualizing the entire large intestine mucosa is produced, for exmpel, by the Israeli company Given Imaging Ltd. and marketed under the brand “M2A® Imaging Capsule”. The M2A® imaging capsule includes a miniature color video camera, a light source, a miniature transmitter and an antenna. The casing of the capsule is produced from a sealed biocompatible special material that is resistant to digestive secretions in the gastrointestinal tract.
The M2A® imaging capsule is swallowed by the patient and conveyed through the digestive tract because of the peristaltic movement of the gastrointestinal musculature. The size of the video capsule is 11×26 mm, its field of view is about 140°, and it weighs about four grams. It can be used to find lesions with a size of less than 0.1 mm. During a normal (eight-hour) examination process, the capsule produces roughly 57,000 images at a rate of two images per second. The capsule is evacuated in a natural way after having passed through the digestive tract.
During its passage through the small intestine, the color video camera takes image sequences that are transmitted in the form of ultrashort waves to a wireless reception unit that is located outside the body, and which the patient carries on a belt around his hips, and are stored in a data recorder after being demodulated and subjected to low-pass filtering and analog-to-digital conversion. The belt, which is comfortable to wear, with the reception unit enables the patient largely to carry on with his customary daily activities during the gastrointestinal examination.
In addition to the image signal, the capsule can also output a locating signal referring to its current position. The point is that it includes metal parts that are located by eight metal detectors applied to the patient's abdominal skin.
It is thereby possible to assign the images to the respective intestinal section. A computer workstation at which the RAPID™ (“Reporting and Processing of Images and Data”) software developed by Given Imaging is installed processes the data and compiles a video film of the small intestine as well as relevant additional information relating to the digestive tract. The doctor responsible has the option of viewing this video film in real time, of tracking the position of the M2A® imaging capsule during its passage through the gastrointestinal tract, and of inspecting individual images exactly in freeze mode and processing and archiving them. The gastroenterologist can then locate any pathologies of the small intestine with the aid of the visual information obtained in this way.
In addition to the application of capsule endoscopy in the region of the gastrointestinal tract, numerous further possible applications are currently being planned. This relates generally to the endoscopic examination of cavities in the interior of the body in which the movement of the video capsule is not prevented by the presence of connective tissue. This includes, for example, the endovascular examination of the cerebral blood vessels, the endoscopic examination of the bronchial tract (bronchoscopy) and the minimally invasive endoscopic examination of the abdominal cavity and the abdominal and pelvic viscera (laparoscopy). When the embodiments of the invention are described below with reference to the gastrointestinal tract, it is to be understood that the embodiments of the invention relates in general to the endoscopy of body cavities.
WO 01/065995 A3 presents a system and an associated method for providing images from the interior of the body of a patient who is to be examined. The system includes an imaging system and an RF transmitter of low signal power for transmitting video signals of a CMOS video camera to a reception system that is located outside the body. The imaging system includes at least one CMOS video camera, at least one light source for illuminating a site in the interior of the body, and an optical lens system for focusing the light beams reflected by the site to be examined.
WO 02/054932 A2 discloses a system and a method for wide angle recording of cavities in the internal organs of a patient that are to be examined. The system includes at least one image sensor, light sources and an optical lens system for recording image sequences from the interior of the body. The system can be integrated in a medical unit or fitted on the latter, which is used for introduction into cavities in the interior of the patient's body. This can be, for example, an advancing endoscope, an injection needle, or else a video capsule that can be swallowed by the patient.
The device described in WO 02/095351 A2 relates to a floating, capsule-type image sensor for examining liquid-filled cavities of organs in the interior of a patient's body that has the specific weight of water or some other volume/mass ratio that permits it to float. In an exemplary embodiment of this, the image sensor includes an imaging system that is installed in a floating housing.
A diagnostic unit, system and method for providing images from cavities of organs in the interior of a patient's body, such as the gastrointestinal tract, for example, is disclosed in WO 03/010967 A1. The unit is a floating capsule that contains an image sensor, a microprocessor and a light source for illuminating a cavity in the interior of the body. Moreover, the unit includes an optical system including a number of filters and positive lenses for focusing the light reflected by the cavity walls. The image data recorded by the image sensor are digitized, compressed and transmitted by an integrated RF transmitter to an RF receiver that is located outside the body and is preferably worn on a belt around the patient's abdomen. The image data received are stored in an internal memory chip of the RF receiver. In an exemplary embodiment of the invention, the reception unit can be connected to a workstation that serves to decompress and condition the data stream for the purpose of visualizing the recorded images.
The disadvantage of the capsule endoscopes described above resides in the inaccurate results of inspection, since the video capsule cannot be controlled and passes too quickly through specific regions in the interior of the body, or does not even record them at all. Moreover, uninterrupted transmission of images from the interior of the body is impossible.